## Solution :

Let the number of boys and girls be x and y, respectively

\(\therefore\) 52x + 42y = 50(x + y)

\(\implies\) 52x + 42y = 50x + 50y

\(\implies\) 2x = 8y

\(\implies\) x = 4y

\(\therefore\) Total number of students in the class

= x + y = 4y + y = 5y

\(\therefore\) Required number of boys

= \(4y\over 5y\) \(\times\) 100% = 80%